September 2011, Vol. 23, No.9

Problem Solvers

Watsonville, Calif., quenches depleted aquifers with recycled water and community education

Problem: Agriculture leads to aquifer depletion and saltwater intrusion into coastal wells

Solution: Water recycling program for agriculture aids in recharging groundwater


The Pajaro Valley is berry country. Decades of intense farming of strawberries, raspberries, lettuce, and other row crops in the 10,000 ha (25,000 ac) east of Monterey Bay in Northern California have strained the region’s aquifers, leading to saltwater intrusion from the bay. The problem was documented as far back as the 1950s, said Mary Bannister, general manager of the Pajaro Valley Water Management Agency (Watsonville, Calif.).

In the agency’s most recent basin management plan, they identified using recycled water for irrigation as a potential solution.

With a Title 16 Bureau of Reclamation grant for $20 million, the agency built a 29,000-m3/d (7.7-mgd) tertiary treatment facility with high-rate flocculation sedimentation, cloth media filtration, and ultraviolet disinfection, as well as coagulant, polymer, and hypochlorite chemical systems. Although the agency paid for the plant and has rights to the recycled water for irrigation, the plant is owned and operated by the City of Watsonville.

This first component of the basin management plan has not been without some issues along the way. Educating the agricultural community about the safety of recycled water was a key component in gaining local acceptance.

“That’s a big deal for us,” Bannister said. “Agriculture, the community, the grower–shippers, the grocery chains, they all need to have a level of understanding about how safe this recycled water is.” She noted that her region was lucky to be introducing its water recycling program soon after another growing region just south of Watsonville had. Because many of the farmers work in both regions, they were already well-versed with recycled water. Despite the challenges, Bannister says the program is a success today, producing about 4.9 million m3/yr (4000 ac-ft/yr) for local agriculture.

“It’s been accepted by the growers, it’s been embraced by the community, and the result of it is that these guys in the coastal area are able to continue farming,” Bannister said.

Educating an agricultural community

The second component of the basin management plan revolves around the recently opened Water Operations Center. The center, which houses the water and wastewater divisions for the city, further stresses the importance of water in a community where every drop is vital. The building is on track for Leadership in Energy and Environmental Design (LEED) Platinum certification, and its water-conscious features are put to use in educating everyone who comes through the doors.

“We never started out as, ‘Let’s aim for a certain LEED certification,’” said Kevin Silviera, wastewater treatment facilities manager for the City of Watsonville. “It was always about what makes the most sense.”

What made sense in the final product was a building that speaks to conservation and thoughtfulness with water.

Both Silviera and Pauline Souza, the sustainability director for the building’s architects, WRNS Studio (San Francisco), highlighted the center’s radiant floor heating and cooling system, which runs recycled water through sub-ground tubing to provide energy-efficient climate control. Souza explained that the designers wanted to display how water runs through the building. They expressed the manifolds in the radiant flooring, showed pipes that lead to each lab bench, and instead of having rainwater run off through gutters, they used rain chains to collect the water. Also, a tiled water fountain at the center is only active when extra recycled water is present, signaling the water’s availability through sight and sound.

“We like the idea of putting water on display, and [the city] did too because so much of what they’re doing is trying to show how a region or people have used or misused water, and how we need to be thoughtful with it,” Souza said. “We bring that now to our projects more than we did before.”

These and other energy-efficient measures in the building make it 54% more energy efficient than California’s Title 24 Energy Efficiency Standards, according to Silviera. He added that once solar panels are installed, the city formally will submit its documentation for LEED Platinum certification.

Until then, the building already has opened its doors to house both the water and wastewater divisions for the city. Silviera said the open design of the center has led to a more cohesive environment and better collaboration between the two groups. “It’s attractive, but it’s also comfortable, which lends itself to higher productivity from employees. [That is] a little harder to measure, but it’s certainly a benefit,” he said.

Additionally, the building and all of its sustainable features are used as an educational tool for the community. An accredited teacher is on staff, and students in Pajaro Valley are brought through the treatment facilities and new water resources center as part of their middle school curriculum.

“The building itself offers a wide variety of green building materials and techniques that were used, which really lends itself to the overall story of the benefits of water recycling,” Silviera said.

©2011 Water Environment Federation. All rights reserved.